Thermographic imaging has proven to be a generally useful technique for detecting structural abnormalities. For example, when exciting a structure with flaws using relatively high ultrasonic power, frictional heating may be generated at the flaws. The flaws can then become detectable under a thermal infrared camera. However, structurally weak regions that may be part of the structure may be vulnerable when subjected to such high ultrasonic power, which could lead to break up of the structure being inspected. Thus, there is a need for further improvements in connection with systems and methods for inspecting a structure.